6,7-dihydro-2H-benzo[6,7]cyclohepta[1,2-c]pyridazin-3(5H)-one → 5-Chloro-3,4-diazatricyclo(9.4.0.0,2,7)pentadeca-1(15),2(7),3,5,11,13-hexaene

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Reaction Steps

Alternatively, 3-oxo-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-c]pyridazine was heated with 20 mL of phosphorus (III) oxychloride at 100° C. for 4.75 h. The solvent was removed under vacuum. The residue was treated with ice and saturated sodium bicarbonate solution. The solid which formed was filtered off, washed well with water and air-dried to yield the corresponding 3-chloro-6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-c]pyridazine (1.6 g); 1H NMR (CDCl3, 300 MHz) 7.82 (m, 1H), 7.44 (m, 2H), 7.39 (s, 1H), 7.27 (m, 1H), 2.55 (m, 4H), 2.32 (m, 2H) ppm; MS (ES) 231/233 (M+H).

Provenance & Evidence